Here is the full list of all 53 The Legend of Heroes: Trails of Cold Steel III achievements.
Mastered Trails of Cold Steel III and earned every achievement.
Opened every treasure chest.
Completed the game on nightmare difficulty.
Completely filled the battle section in the notebook.
Completely filled the books section in the notebook.
Completed all quests, both at the branch campus and during field exercises.
Acquired over a million mira.
Collected all radio material and reported it to Munk.
Achieved instructor rank S.
Completely filled the fish section in the notebook. (All 25 types of fish + Rod Lv. Max)
Forged a strong bond with Kurt.
Forged a strong bond with Ash.
Forged a strong bond with Machias.
Forged a strong bond with Gaius.
Completely filled the character section in the notebook.
Gathered all 28 varieties of master quartz.
Completely filled the recipe section in the notebook.
Completely filled the cards section in the notebook.
Achieved an academy grade of Prestigious.
Initiated 300 advantage encounters (including double and triple advantage).
Earned an S-Rank on any chapter.
Completed the final chapter.
Won 600 battles.
Used 100 S-Crafts in battle.
Completed Chapter 4.
Forged a strong bond with Millium.
Raised any two characters to Link Level 5.
Forged a strong bond with Sara.
Used Rush in battle 100 times.
Forged a strong bond with Laura.
Forged a strong bond with Fie.
Forged a strong bond with Elliot.
Forged a strong bond with Towa.
Forged a strong bond with Jusis.
Forged a strong bond with Altina.
Forged a strong bond with Emma.
Forged a strong bond with Juna.
Forged a strong bond with Musse.
Forged a strong bond with Alisa.
Forged a strong bond with Elise & Alfin.
Took all landscape photos and reported them to Vivi.
Used Burst in battle 50 times.
Won a battle with a tactical bonus of x3.0 or greater.
Inflicted Break over 800 times.
Completed Chapter 3.
Raised a master quartz to level 7.
Completed Chapter 2.
Used over 500 follow-up attacks in battle.
Used Brave Order in battle over 100 times.
Completed Chapter 1.
Won 100 battles.
Completed the prologue.
Completed the orienteering exercise.